Extensions installed by policy overrun previously installed extensions.

chrome/browser/extensions/pending_extension_manager.cc

Index: chrome/browser/extensions/pending_extension_manager.cc
diff --git a/chrome/browser/extensions/pending_extension_manager.cc b/chrome/browser/extensions/pending_extension_manager.cc
index d4446a95c639f1632d1c6cd5da12d72ef88c1166..fece1bebc2c4ff2b3ecdc72d4a993b01a43f3e59 100644
--- a/chrome/browser/extensions/pending_extension_manager.cc
+++ b/chrome/browser/extensions/pending_extension_manager.cc
@@ -68,19 +68,22 @@ bool PendingExtensionManager::AddFromSync(
 
 void PendingExtensionManager::AddFromExternalUpdateUrl(
     const std::string& id, const GURL& update_url,
-    Extension::Location location) {
+    Extension::Location location, bool overwrite) {

[Sam Kerner (Chrome), 2011/08/10 17:21:09]

There are two reasons |overwrite| is useful:

1) The new location has a higher priority than the old one.

2) The extension is already installed, and you want to avoid the LOG(DFATAL).

I would prefer that PendingExtensionManager methods enforce the invariant that
the higher-ranked location wins.  Instead of adding the overwrite parameter,
lets solve #1 by using Extension::GetHigherPriorityLocation() to see if an
existing record should be overwritten.  #2 can be solved by LOG(DFATAL)ing only
when the new location does not outrank the old location.

[Joao da Silva, 2011/08/11 10:03:23]

Done.

   CHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
 
   const bool kIsFromSync = false;
   const bool kInstallSilently = true;
 
-  if (service_.IsExternalExtensionUninstalled(id))
-    return;
+  if (!overwrite) {
+    if (service_.IsExternalExtensionUninstalled(id)) {
+      return;
+    }
 
-  if (service_.GetInstalledExtension(id)) {
-    LOG(DFATAL) << "Trying to add extension " << id
-                << " by external update, but it is already installed.";
-    return;
+    if (service_.GetInstalledExtension(id)) {
+      LOG(DFATAL) << "Trying to add extension " << id
+                  << " by external update, but it is already installed.";
+      return;
+    }
   }
 
   AddExtensionImpl(id, update_url, &AlwaysInstall,